Sulfonate composition and preservative composition comprising the sulfonate composition

ABSTRACT

A sulfonate composition obtainable by a process in which a naphthalene ring-containing sulfonic acid is reacted with an amine in the presence of a base oil at a temperature in the range of from 20-80° C. The molar ratio of the sulfonic acid to the amide is in the range of from 0.2-3 (S/A). The invention also provides a preservative composition comprising the present sulfonate composition; a metal article having a coating thereon which coating comprises the present preservative composition; a process for preparing the sulfonate composition; the use of the present sulfonate composition to prevent and/or reduce corrosion in a roll bearing system; and the use of the present preservative composition to prevent and/or reduce corrosion in a roll bearing system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 102019206560.0, filed May 7, 2019, the contents of which is fully incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a sulfonate composition; a preservative composition comprising the sulfonate composition; a metal article having a coating thereon which coating comprises the preservative composition; a process for preparing the sulfonate composition; the use of the sulfonate composition to prevent and/or reduce corrosion in a roll bearing system; and the use of preservative composition to prevent and/or reduce corrosion in a roll bearing system.

BACKGROUND OF THE INVENTION

Preservative compositions are widely used to protect bearings and other structural components against damages which are the result of for instance corrosion, wear and surface cracking initiation. Damages to bearings and roll bearing systems will affect their performance and functioning during life time at the operating conditions and affects the bearing life.

A common type of bearing damage is fretting. Fretting refers to any situation in which the mating surfaces are subjected to small amplitude reciprocating sliding or rolling motions. Fretting can occur between mating surfaces which are intended to be fixed but are subjected to small oscillating motions to due vibration. In various applications, bearings in housings or bearing on shafts, can be subjected to dynamic loads or bending moments introducing small amplitudes of small amplitudes of relative motion. Fretting can cause seizure, can amplify vibrations, cause wear and fatigue of the components and might eventually lead to failure of the system. Fretting is characterized by the fact that the wear debris stays entrapped in the contact due to the small vibration amplitudes of fretting. In conventional atmospheres, oxidation of the debris is involved and the terms fretting corrosion and fretting wear are often applied. The term false brinelling is specifically used for fretting of point contacts in ball bearings.

Bearings of passenger cars can be subjected to small oscillating motions and as a result could reveal false brinelling after car transportation. The appearance of fretting in a ball-on-ring contact resembles a Brinell indentation used in hardness measurements of bulk materials, hence false brinelling. System vibrations and/or cyclic loading, can both result in relative sliding of the mating surfaces over each other and within these aspects two different terminologies are being used. Often a distinction is made between fretting wear and fretting fatigue.

Fretting fatigue generally refers to dynamic bulk stresses including tensile stressing of the component. Fretting conditions induce crack initiation and propagation at stresses below the fatigue limit of the component. Fretting wear and fatigue can both involve dynamic loads. Fretting wear is an adhesive wear mechanism. The difference between fretting wear and fatigue is the dominance in which the dynamic bulk stresses (those resulting in tensile stresses) are participating in the failure mode relatively to (dynamic) shear stresses. Such tensile stress can be responsible for through cracking of the component. The shear stresses decrease rather rapidly with the distance beneath the surface and in the absence of tensile bulk stresses, cracking is restricted to shallow surface regions. Under these conditions, fretting wear overshadows fretting fatigue and cracking becomes limited to shallow depths.

Another common type of bearing damage is frictional corrosion which occurs in the form of a chemical reaction which is activated by relative micro movements between contacting surfaces under certain conditions inside a bearing. The frictional corrosion takes place in the form of fretting corrosion or vibration corrosion.

Fretting corrosion occurs when there is a relative movement between a bearing ring and shaft or housing, because e.g. the fit is too loose or too tight. Due to relative movement between the mating surfaces small particles of material may become detached from the surface, and these particles may oxidize quickly when exposed to the oxygen in the atmosphere.

Vibration corrosion, also called false brinelling, occurs in in rolling element-raceway contact areas due to micro-movements and/or resilience of the elastic contact under cyclic vibrations. Depending on the intensity of the vibrations, the lubricating condition and load, a combination of corrosion and wear occurs, forming shallow depressions in the raceway. In the case of a stationary bearing, e.g. bearings during transportation of passenger cars, the depressions appear at rolling element pitch and can often be discolored or shiny. Bearing and other metal components are subjected to machining processes, cleaning, heating and other chemical treatments and can face during its production processes various chemical and corrosion aggressive compounds from which the metal surfaces need to be protected.

Rust preventives and corrosion inhibitors are providing resistance to these corrosion promoting fluids and environments. After manufacturing the bearing surface can be dipped or sprayed into a preservative fluid. A temporary protecting film can protect the metal and bearing surface against corrosion during shipment and storage of the metal component. A corrosion inhibitor can be applied as an additive in a lubrication oil or grease or even as part of a processing fluid. As long as the carrying fluid or grease is able to make a film over the metal surface than the corrosion inhibitor task is to prevent the surface from corrosion.

Rust preventives are usually composed from additives dissolved in a medium. The medium can be as much as 80 wt. % or even higher present in the preservative composition. Popular media are solvents, naphthenic or paraffinic oils. Solvents can have the capacity to completely evaporate while oils usually do not fully evaporate after application and oily films remain on the surface. Water can partially or fully evaporate and as a result could still be part of the final film even after application or drying. Examples of additives used in preservatives are metal salts, waxes, oils, petroleum based products, mineral spirits or other types of additives. Waxes and metal salts are commonly applied as ingredients in the preservatives. Typical examples of metal salts are calcium, barium, sodium sulfonate salts. The use of these typical metal salts do not have fully satisfying corrosion protection and require the need of waxes. Some of these metals salts have their limitation either in use due to their stringent safety and environmental legislations or simply due to their poor corrosion resistance. Waxes are prone to quality inconsistency, unstable crystallinity and can show issues with sprayability.

Conventional preservative compositions are usually composed of metal-containing compounds and waxes. Typical metal-containing compounds used for this purpose are calcium sulfonate salts that are incorporated in the solvent or oil. Another drawback of conventional preservative compositions is the fact that their effectiveness leaves considerable room for improvement.

Object of the present invention is to provide new approach to attractively prevent and/or reduce corrosion in which no use is made of metal salts and waxes. This new approach is based on the preparation of a new chemical composition which displays excellent and resistance to corrosion, in particular moisture corrosion, standstill corrosion and stress corrosion cracking.

Another object of the present invention is to provide a preservative composition which comprises the new chemical composition.

SUMMARY OF THE INVENTION

Surprisingly, it has now found that a particular sulfonate composition prevents and/or reduces moisture corrosion in an excellent manner.

Accordingly, the present invention provides a sulfonate composition obtainable by a process in which an aromatic ring-containing sulfonic acid is reacted with an amine in the presence of a base oil at a temperature in the range of from 20-80° C., and wherein the molar ratio of the sulfonic acid (S) to the amide (A) is in the range of from 0.2-3 (S/A).

The sulfonate composition in accordance with the present invention displays unique properties in terms of moisture corrosion prevention and/or reduction. The present sulfonate composition prevents and/or reduces moisture corrosion, in particular standstill corrosion in an improved way when compared to conventional preservative compositions that contain calcium sulfonate salts.

DETAILED DESCRIPTION OF THE INVENTION

The present sulfonate composition is obtainable by reacting a an aromatic ring-containing sulfonic acid with an amine in the presence of a base oil. Preferably, the aromatic ring-containing sulfonic acid is a naphthalene ring-containing sulfonic acid. Good results can also be achieved with linear alkylbenzene sulfonic acid, branched alkylbenzene sulfonic acids or with or without unsaturated bonds in the hydrocarbon chain.

In accordance with the present invention an aromatic ring-containing sulfonic acid is reacted with an amine. The sulfonic acid can be aliphatic, branched, unbranched, saturated or unsaturated, aromatic as long as the end of the hydrocarbon chain has the sulfonic configuration.

Preferred embodiments of the present invention are naphthalene sulfonic acid, anthracene sulfonic acid, phenanthrene sulfonic acid and benzene sulfonic acids.

The naphthalene ring-containing sulfonic acid is suitably selected from the group consisting of naphthalene sulfonic acid, anthracene sulfonic acid, and phenanthrene sulfonic acid. Preferably, the naphthalene ring-containing sulfonic acid is naphthalene sulfonic acid.

Preferably, the amine is a fatty acid amine. In the context of the present application fatty acid amines are defined as amines derived from fatty acids. It will be understood that fatty acids are aliphatic monocarboxylic acids derived from, or contained in esterified form in an animal or vegetable fat, oil or wax. In accordance with the present invention use can be made of natural and synthetic fatty acids. Suitably, the amine to be used in accordance with the present invention is a fatty acid that contains one or more unsaturated C—C bonds in which a NH₂ group is introduced somewhere in the unsaturated fatty acid chain.

Primary, secondary, tertiary and cyclic amines exist. Organic amines include amino acids, trimethylamine, aniline and biogenic amines. Fatty amines has an amine attached to a hydrocarbon chain and the fatty amines is part of the oleochemical functional groups being derived from plant and animal fats.

The amines to be used in accordance with the present invention can for instance be formed from ammonia in an alkylation reaction with alcohol in the presence of ammonia and in the presence of catalysts. Hydrogenation reduces nitriles to amines in the presence of a catalyst. Reaction of haloalkanes with ammonia and amines forms different type of amines. Lithiumaluminiumhydride reduces amides to amines. Many amines are produced from aldehydes and ketones via reductive amination, which can either proceed catalytically or stoichiometrically. Ammonium salts which can provides beneficial effects to the grease composition of the present invention can be formed from amines and halocarbons.

The amines may also be formed by the hydrolysis of alkyl isocyanate, or by degradation of the acid amide with aid of hypochlorite, hypobromite, halogen, or in combination with a base, the conversion of the corresponding acid azide with aid of an acid chloride with sodium azide resulting in amine hydrochloride, or reduction of a cyanide or of acid amide.

Commonly applied amines can originate from aliphatic and aromatic, saturated and unsaturated amines. Saturated amines can be branched or unbranched.

The preferred embodiments of the present invention have a NH2 at the end of the hydrocarbon chain. Aliphatic, aromatic, saturated, unsaturated, branched or unbranched or other type of amines are part of the present invention as long as one end of the hydrocarbon chain has a NH2 configuration.

An aliphatic unsaturated fatty amine comprises preferably 2-24 carbon atoms.

Commonly applied amines can originate from saturated and unsaturated fatty acids like lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, lauroleic acid, myristoleic acid, palmitoleic acid, gadoleic acid, erucic acid, ricinoleic acid, linoleic acid, linolenic acid, eleostearic acid, arachidonic acid, phenylstearylamine and clupanodic acid. The amines of the foregoing acids may be obtained by transformation to the acid amide followed by reduction with sodium in absolute alcohol. Other sources of mixed amines are known to the art.

The unsaturated fatty amines as part of the here presented invention are prepared and formed from ammonia of which one or two hydrogens are substituted by hydrocarbon chain of a length from 18 C-atom or more and having 1 to 3 unsaturated carbon bonds. Commercial unsaturated fatty amines are blends of fatty amine of various hydrocarbon chain length and comprising of 1 to 3 unsaturated carbon bonds. These blended compositions can have various wt. % of unsaturated fatty amines. These mixed fatty amines can be further processed to obtain the desired quantity of unsaturated amines and to control these amounts by applied processing techniques of decanting, steam distillation or other processing techniques. Examples of unsaturated fatty amines are oleylamine, linoleylamine, linolenylamine, arachidylamine, eleostearylamine, erucylamine, petroselenylamine, and palmitoleylamine. The amine to be used can be saturated or unsaturated, branched or unbranched C2-C22 amines. Preferably, the C2-C22 amines are saturated amines.

The fatty acid from which the fatty amine can suitably be prepared comprises 2-24 carbon atoms. A suitable example is for instance oleic amine. Suitably, the amines are metal salts. When the amines are metal salts, the amount of metal (salt(s) is in the range of from 0.1-40% by weight, based on the total weight of the grease composition.

Suitably, the amines to be used in accordance with the present invention contain one or more unsaturated C—C bonds and/or at least one OH group. Suitably, the amines to be used in accordance with the present invention contain one or more unsaturated C—C bonds and at least one OH group. Suitably, the amines contain two or more unsaturated C—C bonds. Suitably, the amines contain two or more unsaturated C—C bonds and at least one OH group, preferably at least two OH groups. Suitably, the unsaturated amines further include at least one OH-group. Suitable examples of such amines are ethyl hydroxy stearamine and bishydroxyethyl oleylamine, and diamines such as bishydroxyethyl oleylamine. Diamines affects the molar ratio, but a person expert in the here presented field of expertise will understand that the molar ratio is affected. This variable is part of the invention although not further explained.

The one or more unsaturated amines may suitably in addition contain at least one OH group, suitably at least two OH groups. Suitably, the one or more amines contain two or more unsaturated C—C bonds and at least one OH group. Suitably, the one or more amines are metal salts. The amines may contain an ester group.

The amine to be used is suitably selected from the group consisting of stearylamine, butylamine, pentylamine, hexylamine, heptylamine, amine and octylamine.

In the process for preparing the present sulfonate composition the naphthalene ring-containing sulfonic acid and amine are reacted in the presence of a base oil. A variety of base oils can be used, provided that they provide a good solubility. Suitable examples of base oils include Group I, II, III, IV and V oils, and polyalfaolefins.

In accordance with the present invention also use can be made of one or more solvents. Preferably, the one or more solvents are selected from the group consisting of polar solvents, non-polar solvents and aprotic polar solvents. Suitable examples of polar solvents include formic acid, n-butanol, isopropanol, nitromethane, ethanol, methanol, acetic acid and water. Suitable examples of non-polar solvents include hexane, benzene, toluene, 1,4-dioxane, chloroform and diethyl ether. Suitable solvents of aprotic solvents include dichloromethane, N-methylpyrrolidone, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide and propylene carbonate. Preferred solvents to be used in accordance with the present invention include dimethyl sulfoxide, acetone, chloroform, ethyl ether, n-hexane, benzene, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, N-methyl-2-pyrolidone and water.

Suitably, the molar ratio of the amine (A) to the polyalfaolefins (P) is in the range of from 1-200 (A/P), preferably in the range of from 25-75 (A/P). In the process the temperature is in the range of from 20-80° C., preferably in the range of from 30-80° C., more preferably in the range of from 40-80° C., and most preferably in the range of from 50-70° C.

In the process the molar ratio of the sulfonic acid (S) to the amine (A) is in the range of from 0.2-3 (S/A). Preferably, the molar ratio of the sulfonic acid (S) to the amine (B) is in the range of from 0.6-1 (S/A), and more preferably in the range of from 0.6-1 (S/A).

In a particularly attractive embodiment of the present invention the naphthalene ring-containing sulfonic acid is naphthalene sulfonic acid and the amine is an aliphaticamine.

In accordance with the present invention the sulfonate composition may also include an emulsifier. The emulsifier can be anionic; it may be a sulfate, sulfonate, or phosphate ester; it may contain cationic head groups; it may include zwitterionic surfactants; it may be nonionic. Suitable examples include ethoxylates such as fatty alcohol ethoxylates; special ethoxylated fatty esters and oils; ethoxylated amines and/or fatty acid amides; and terminall blocked ethoxylates. Other suitable examples of emulsifiers include fatty acid esters of polyhydroxy compounds such as fatty acid esters of polyhydroxy compounds; fatty acid esters of glycerol; fatty acid esters of sorbitol; fatty acid esters of sucrose; and alkyl polyglucosides. Other suitable emulsifiers include amine oxided, sulfoxides, and phosphie oxides such as sodium phosphates; mono- and diglycerides; sodiu stearoyl lactylate; esters of monoglyceride; and simple cellulose.

The present invention also provides a preservative composition which comprises the sulfonate composition in accordance with the present invention. In addition to the present sulfonate composition, the preservative composition may contain additives such as emulsifiers, corrosion inhibitors, and lubricating improvers.

The preservative compositions according to the present invention include anti-rust preservative compositions and anti-corrosion preservative compositions. Suitably, the preservative composition comprises 0.2-50% by weight of the sulfonate composition, preferably at least 0.5-40% by weight, and more preferably at least 0.5-30% by weight, based on the total weight of the preservative composition. Preferably, the preservative composition according to the present invention contains an anhydride amide and/or an anhydride amine.

In addition, the sulfonate composition may include unreacted amine. Suitable anhydride amides include pyromellitic dianhydride amide, succinic acid anhydride amide and maleic acid anhydride amide. Preferred anhydride amides include succinic acid anhydride amide and maleic acid anhydride amide. More preferred anhydrides are succinic acid anhydride amide and maleic acid anhydride amide.

The anhydride amide or anhydride amine can be prepared by reacting an anhydride with an amine.

In case the anhydride is succinic acid anhydride, the anhydride amide can suitably be prepared by reacting the succinic acid anhydride with an amine, whereby the molar ratio of the succinic acid anhydride (SAA) to the amine (A) is in the range of from 0.2-3 (SAA/A), preferably in the range of from 0.5-2.5 (SAA/A), more preferably in the range 0.75-1.25 (SAA/A), and most preferably in the range of from 0.95-1.05 (SAA/A).

In case the anhydride is maleic acid anhydride, the anhydride amide can suitably be prepared by reacting the maleic acid anhydride with an amine, whereby the molar ratio of the maleic acid anhydride (MAA) to the amine (A) is in the range of from 0.5-3 (MAA/A), preferably in the range of from 0.1-2.5 (MAA/A), more preferably in the range of from 1-2.25 (MAA/A), and most preferably in the range of from 1-2 (MAA/A).

In a particularly attractive embodiment of the present invention the naphthalene ring-containing sulfonic acid is naphthalene sulfonic acid, and the anhydride amide is succinic acid anhydride amide and/or maleic acid anhydride amide.

The present invention also relates to a process for preparing the sulfonate composition according to the present invention, which process comprises the step of reacting a naphthalene ring-containing sulfonic acid with an amine in the presence of a base oil at a temperature in the range of from 20-80° C., wherein the molar ratio of the sulfonic acid (S) to the amine (A) is in the range of from 0.2-3 (S/A).

The present invention also relates to a metal article having a coating thereon which coating comprises the preservative composition according to the present invention. Suitably, the metal article is a rolling element. Preferably, the metal article is a bearing. An advantage of the sulfonate composition according to the present invention is that it has very attractive film forming properties which allows for excellent coatings to be formed on the metal articles.

The sulphonate composition or preservative composition according to the present invention can be used to prevent and/or reduce corrosion, in particular moisture corrosion, standstill corrosion, stress corrosion cracking or any other form of corrosion for components, surfaces or metal articles like housing bearing seats, shaft bearing seats, spacer surfaces, guide ring surfaces, seal surfaces, seal seat surfaces or any other surfaces that are facing oscillating motions and/or vibrations and/or any forms of corrosion. The sulphonate composition or preservative composition according to the present invention can be used on the surfaces of metal articles but also on non-metal surfaces like plastic material surfaces, glass material surfaces and plastic material surfaces.

In addition, the present invention relates to the use of the present sulfonate composition for preventing and/or reducing moisture corrosion, in particular standstill corrosion, in a roll bearing system.

Further, the present invention relates to the use of the preservative composition according to the present invention for preventing and/or reducing moisture corrosion, in particular standstill corrosion, in a roll bearing system. 

1. A sulfonate composition obtainable by a process in which a naphthalene ring-containing sulfonic acid is reacted with an amine in the presence of a base oil at a temperature in the range of from 20-80° C., and wherein the molar ratio of the sulfonic acid to the amine is in the range of from 0.2-3.0.
 2. The sulfonate composition according to claim 1, wherein the sulfonic acid is selected from the group consisting of naphthalene sulfonic acid, anthracene sulfonic acid and phenanthrene sulfonic acid.
 3. The sulfonate composition according to claim 1, wherein the naphthalene ring-containing sulfonic acid is naphthalene sulfonic acid.
 4. The sulfonate composition according to claim 1, wherein the amine is a fatty acid amine.
 5. The sulfonate composition according to claim 1, wherein in step (a) the molar ratio of the sulfonic acid to the amine is in the range of from 0.5-1.0.
 6. The sulfonate composition according to claim 5, wherein the temperature in step (a) is in the range of from 40-80° C.
 7. A preservative composition comprising the sulfonate composition according to claim
 1. 8. The preservative composition according to claim 7, comprising in addition an anhydride amide and/or an anhydride amine.
 9. The preservative composition according to claim 8, wherein the anhydride amide is succinic acid anhydride amide or maleic acid anhydride amide.
 10. A metal article having a coating thereon that comprises the sulfonate composition according to claim 1 or the preservative composition according to claim
 8. 11. A process for preparing the sulfonate composition according to claim 1, wherein a naphthalene ring containing sulfonic acid is reacted with an amine in the presence of a base oil at a temperature in the range of from 20-80° C., and wherein the molar ratio of the sulfonic acid to the amine is in the range of from 0.2-3.0.
 12. Use of the preservative composition according to claim 7 to prevent and/or reduce corrosion in a roll bearing system.
 13. Use of the sulfonate composition according to claim 5 to prevent and/or reduce corrosion in a roll bearing system. 